This invention relates to auxiliary fuel systems and, in particular, to a fuel manifold for a crashworthy, auxiliary fuel system for a helicopter.
Auxiliary fuel tanks have long been used to extend the range of a helicopter and other aircraft or to provide refueling capability at a remote location. Depending upon the size and type of helicopter, auxiliary fuel tanks have been located in pods outside the helicopter, under seats, in cargo bays, and elsewhere. For some applications, e.g. surveillance or patrol, an added fuel tank may be an essentially permanent installation. For rescue or other operations, it is desirable that an auxiliary fuel tank be easily installed or removed in order to re-configure a helicopter as quickly as possible; e.g. in ten minutes or less.
Adding an auxiliary fuel tank is not merely a matter of attaching the necessary components and tapping into the existing fuel system of the aircraft. All existing structures and systems are designed to meet minimum requirements for airworthiness. Thus, one cannot simply cut or drill into a bulkhead to mount an auxiliary fuel tank. Ideally, an auxiliary fuel system will require no modification of the airframe and minimal changes to existing fuel systems.
A problem with many auxiliary fuel systems in the prior art is that the system is not crashworthy. As used herein, a "crashworthy" fuel system is one that will not have dangerous spillage of fuel when subjected to an upper limit, survivable crash.
The conflicting requirements of crashworthiness and ease of installation or removal are difficult to meet simultaneously. An existing modification of an Apache helicopter includes auxiliary fuel tanks on the outside of the craft wherein the tanks are normally vented to atmosphere and pressurized with air for fuel transfer to main tanks. (The main fuel system in an Apache helicopter is nitrogen filled).
In view of the foregoing, it is therefore an object of the invention to provide a fuel manifold that does not require modification of an airframe.
Another object of the invention is to provide a manifold that is compatible with nitrogen filled fuel tanks.
A further object of the invention is to provide a compact manifold that can remain in the aircraft when the auxiliary fuel tank is removed and that does not interfere with other uses of the space for the auxiliary fuel tank, such as storing an ammunition magazine, or interfere with the normal operation of the main fuel system or other aircraft systems.
Another object of the invention is to provide a manifold that is quickly and easily connected to an auxiliary fuel tank.